Measured application of potent and/or concentrated liquids requires the addition thereof to liquid carriers in minute proportions, and to these ends liquid proportioners and the like are widely used and characterized by complexity and considerable expense. And with the prior art complexities, reliability and accuracy of such devices has been questionable especially, for example, in titrating a water line at relatively constant parts per million to be distributed as a fertilizer. In such a case, an overdosage can be extremely harmful and an underdosage rather useless. Furthermore, the water line pressures vary with different installations and all of which is upsetting to balance and accuracy, and all of which is difficult to cope with in usual systems. For instance, irrigation by use of sprinklers is widely used and is met with varied rates of flow and pressure; and it is under these circumstances that a liquid metering device must be made to operate with predetermined accuracy. To these ends therefore, I have provided a new and useful apparatus in the form of a liquid dispenser which is readily adapted to the flow and pressure factors which prevail, so as to be adjusted to dispense a relatively constant ratio of liquid additive into a liquid flow line.